Some of the additional material surfaced as a result of The Australian newspaper's investigative podcast, The Teacher's Pet.

Ms Dawson was 33 when she went missing in January 1982 leaving behind two young daughters.

Detectives from the NSW homicide squad began reinvestigating her suspected murder in 2015 and sent a brief of evidence to the Director of Public Prosecutions in April this year.

Chris Dawson, a Newtown rugby league player in the early 1970s, has long been a suspect in the case but denies any involvement in his wife's disappearance.

Despite the fact Ms Dawson's body has not been found, investigators are confident of the strength of their case.

"There are other examples in policing history, and history of the courts, where people have been convicted of murder without a body," NSW Detective Superintendent Scott Cook told reporters on Wednesday.

Ms Dawson's relatives expressed relief following the arrest, while Chris Dawson's family said they had no doubt he would be found innocent.

Detectives in September dug up the backyard at the Bayview home the couple shared in the early 1980s but did not find her remains or items of interest.